Problem: $ { \left[\begin{array}{rr}{-1} & {-1} \\ {3} & {3} \\ {-1} & {1}\end{array}\right]-\left[\begin{array}{rr}{3} & {3} \\ {4} & {2} \\ {3} & {3}\end{array}\right] = {?} } $
Explanation: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}-{3} & {-1}-{3} \\ {3}-{4} & {3}-{2} \\ {-1}-{3} & {1}-{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-4} & {-4} \\ {-1} & {1} \\ {-4} & {-2}\end{array}\right]}$